Nope, I wouldn't be happy to send the item to Brazil as the tracking information will likely be limited and as a result a high liklihood of the buyer saying it never arrived.
As for Greece, I once sold a game to someone in Portugal and there were no problems, and I think you can get things internationally tracked so less issues there.

Quote them extortionate postage (secure tracking through a parcel company), they won't pay, you will be able to dispute it, then offer to someone else or relist! If they do pay the postage then you know its secure. It's their fault for not asking you the cost of the postage in the first place.

Just had a look at the listing,regardless of the buyer having zero feedback you have underquoted p&p,you've quoted £5 for airsure to brazil,the cheapest airsure to brazil at 100g costs £6.72,rising as the weight increases,so your going to lose out there for sure,

You are obliged to post it to them if they pay or risk negative feedback & a report of seller non performance

Just had a look at the listing,regardless of the buyer having zero feedback you have underquoted p&p,you've quoted £5 for airsure to brazil,the cheapest airsure to brazil at 100g costs £6.72,rising as the weight increases,so your going to lose out there for sure,

You are obliged to post it to them if they pay or risk negative feedback & a report of seller non performance

That's true, see if you could talk to the buyer and convince him that the game won't work in consoles in Brazil.